There is no such thing as bug free solutions. Zero defects – is just human definition of what a defect is – oh, and the acceptance criteria of no severity 1-critical defects, is always negotiable. Acceptance of the delivery may be outside the test result… You always find things, you always choose how to handle them. There is always a threshold on what you want to fix. What sets you apart from others is HOW you handle the unexpected issues you DO find.
Google has Canary builds, Spotify their chaos monkeys, others have continuous delivery. Some even test in the Wild. How you choose to handle the things discovered is – a choice, similarly as it is a choice to handle them at all.
In all business environments errors happen – even or context new issues / bugs / defects / findings / incidents… happens, when you evaluate (test) a solution. Even in the strictest GxP Pharma validation there will be situations that is not specifically on par with the reviewed and approved scripts. Even the best CMMi or ISO29119 accredited company will stumble into new information, or test only limited subsets of total coverage.
If you fail to prepare for the unexpected – you chose poorly.